Microstructure Defects Contributing to the Energy Absorption in CrMnNi TRIP Steels

Abstract

Freiberg for the hot rolled TRIP steel samples. For the metallographic sample preparation we would like to thank Mrs. Dipl.-Ing. A. Mueller, Mrs. K. Becker; for the conventional preparation of TEM samples and the FIB preparation of TEM samples on Infineon, Dresden we would like to thank Mrs. Dipl.-Ing. A. Leuteritz.Microstructure defects control the TRIP effect and/or the TWIP effect and contribute significantly to the absorption of deformation energy in plastically deformed austenitic CrMnNi steels. In this study, the propagation and interaction of dislocations, stacking faults and twins connected with the formation of Lomer-Cottrell locks, stacking fault tetrahedra, dislocation clusters, deformation bands, microtwins with high-energy incoherent twin boundaries and the nucleation of a 0martensite in the areas of the high local lattice strain due to the fluctuation of the stacking fault density and the lattice shearing, were analysed in the CrMnNi TRIP steel after different deformation extents via transmission electron microscope with high resolution and via scanning electron microscope. ADVANCED ENGINEERING MATERIALS 2013, 15, No. 7

Peculiarities of deformation of CoCrFeMnNi at cryogenic temperatures

“…(ii) In certain cases, only diffuse stacking fault arrangements are formed by deformation in TWIP/TRIP steels, as observed by Borisova et al [48]. These should not be treated as compact aggregates of ε-martensite and would not be identified as such by EBSD [48,49]. (iii) According to the reasoning provided in Ref.…”

Nanoindentation measurements on deformation-induced α’-martensite in a metastable austenitic high-alloy CrMnNi steel

“…A sigmoidal shape of the stress-strain curve is a good indicator for the martensitic phase transformation, visible in the electron backscattering diffraction (EBSD) maps in Figure 1b and c. During tensile deformation, deformation bands (yellow) with a hexagonally indexed lattice structure and a thickness of a few micrometres or less develop. In references [19][20][21], it was shown that the hexagonally indexed regions (usually called ε-martensite) are formed by a high density of stacking faults. These bands and their intersection points are nucleation sites for α'-martensite (blue) with a size in the order of few μm or less [19,22] as shown by the orientation map in Figure 1c.…”

“…In references [19][20][21], it was shown that the hexagonally indexed regions (usually called ε-martensite) are formed by a high density of stacking faults. These bands and their intersection points are nucleation sites for α'-martensite (blue) with a size in the order of few μm or less [19,22] as shown by the orientation map in Figure 1c.…”

Deformation Mechanisms in Austenitic TRIP/TWIP Steel as a Function of Temperature

“…[21] Because of a high density of SFs in the deformation bands of the austenite, hexagonal areas are formed, which appear as hcp phase (e-martensite) in X-ray diffraction experiments or in TEM and EBSD investigations. [22,23] Therefore, a continuous phase transformation sequence c fi e fi a¢ is often found in this type of steels. Via the c fi e fi a¢ transformation route, the nucleation of the a¢-martensite needs much less activation energy than the c fi a¢ route.…”